The present invention relates generally to crop harvesting machines, commonly referred to as combines, and, more particularly, to providing a mechanism for adjusting the cutting angle of the header platform knife.
Combines, particularly the self-propelled type, are equipped to utilize a variety of crop harvesting headers, including headers specifically designed for harvesting corn, cereal grains and soy beans. Normally, these headers are attached to the forward end of the feeder house, which is a structure used to convey crop material from the header to the combine base unit for further harvesting treatment. As is shown in U.S. Pat. No. Reissue 26,512, the forward end of the feeder house can be constructed so that the header can be quickly and easily attached thereto. Usually, the feeder house structure is rectangular in shape and includes a rectangular crop inlet opening at the forward end.
Prior art cutting angle adjustment mechanisms are represented by U.S. Pat. No. 3,474,606 and U.S. Pat. No. 3,638,407. In general, these devices rely on a pivotal mounting directly between the header and the feeder house to swing the header away from the feeder house and thereby change the angular relationship between the header cutting means and the ground. One particular problem common to such devices is that, when the header swings away from the feeder house, the distance between the header and the feeder house increases, resulting in a less effective operation of the crop conveyor within the feeder house structure to engage crop material and transport it rearwardly.
This change in cutting angle is particularly significant for the harvest of soy beans. Because the grain portion of this crop lies closer to the ground than most grain crops, it is advantageous to bring the header cutterbar closer to the ground to reduce crop loss even though the potential for damaging the cutterbar by impacting it into the ground is increased. Also, since changes in cutting angle are directly related to the size of tires used on the combine, it is desirable to have the capability to vary the cutting angle in response to tire size changes.